Bag closing mechanism



Oct. 19, 1954 C:- B, HARKER 2,691,857

BAG CLOSING MECHANISM Filed Feb. 19, 1953 2 Sheets-Sheet l Chawla E) CMQ kaf J ZJ-ndr (01%' CBT-romsx/ Oct. 19, 1954 c. B. HARKER BAG CLOSING MECHANISM 2 Sheets-Sheet 2 Filed F'ebA 19, 1955 Charleu Q4 v'KQA/q C,. my M w 'G17 I a chute of a thermoplastic material and the walls of Patented Oct. 19, 1954 BAG CLOSING MECHANISM Charles E. Harker, Rockford, lill., assignor to Bartelt Engineering Company, Rockford, Ill., a corporation of Illinois Application February 19, 1953, Serial No. 337,704

9 Claims.

. 1 This rinvention relates `-to a packaging machine of the type in which a row of Abags are supported open end up on a carrier and ad- -vanced step by step to present each bag suc- -cessively to a filling station and then a closing station where the upper end portions of the bag Walls are sealed together to close the bag.

The general object is to provide in a machine of the above character anew and improved closing mechanism which holds the upper ends of Ythe bag walls straight and alined while being sealed so that the resulting seal is neat and even.

A more detailed object is to support each bag on the carrier by a gripper which holds the leading edge of the bag and to grip and hold the ltrailing edge of the bag as the latter approaches -the closing station whereby the final movement of the bag into this station stretches the bag across its width thus straightening the upper Yedges of the bag walls preparatory to sealing.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a fragmentary side elevation of -a packaging machine vincorporating the novel features of the present invention.

Fig. 2 is a sectional View taken along the line 2 2 in Fig. 1.

Fig. 3 is a top View of the bag stretching mechanism with parts broken away.

Fig. 4 is a perspective View of a bag filled by the packaging machine.

For the purpose of illustration, the invention is shown in the drawings embodied in a packaging machine in which a carrier 5 grips and supports a succession of bags 6 in spaced relation and open end up and advances the bags edgewise step by step through a filling station 1, a .station 8 at which the bag is closed by sealing the upper edges of the bag walls together as indicated at 9, and a discharge station I0 where the bags are released and dropped through I I. Preferably, the bags are made each bag are joined together along their side edges by heat seals I2 and I 3.

The various mechanisms used in the packaging operations are mounted on an elongated horizontal frame I4 and are operated in timed relation to each other from a horizontal cam- 'sha'ft I5 paralleling the path of advance of the bags and driven continuously by ra'suitable motor -(-not shown). The carrier or conveyor 5 may mittently from the be an endless chain I6 having a lhorizontal Arun through the operating stations and driven intercamshaft through a conventional Geneva mechanism II driving a sprocket wheel I8 around which the chain is wound, so that the bags are presented successively to and dwell at the iilling, closing and discharge stations. Spaced evenly around the chain and rigidly mounted thereon are a plurality of grippers I9. The latter comprise two vertically spaced clamps V2li and 2l open-ing rearwardly of the conveyor advance and gripping the leading edge seal I.2 immediately below the closing seal 9 and near the bottom of the bag respectively.

At the filling station -'I, material to be packaged is delivered to the bag through a spout 22 disposed above the bag at this station and the material is dispensed through 'the spout during Adwelling of the bag through the action of a suitable mechanism (not shown) actuated by the camshaft I5. After being filled, the bag is advanced to the closing station 3 where, during a dwell, the upper edge Vportions of the bag walls are joined together by sealing elements 23, herein heated shoes, which form the closing seal v9. The shoes 23 are disposed immediately above the upper clamp 20 of the gripper I 9 and are mounted on the upper ends of upright levers 24 which are pivoted intermediate their ends on the frame I4 to swing together and apart and press the shoes momentarily against the bag walls. Swinging of the levers during dwelling of the bags is eTected by cams 25 fast on the camshaft I5 and engaging follower rollers 26 on the lower ends of the levers.

When the bag is lled, the bag walls bulge outwardly due to the material in the bag. Although the leading edge I2 of the bag is held straight by the spaced clamps 25 and 2I of the gripper I9, the trailing edge I3 may bend inwardly opening the mouth of the bag and bowing the upper ends -of the bag walls giving the bag an irregular shape such as shown in Fig. 4 in solid lines. As a result, it has been diiicult heretofore to obtain a neat closing seal 9 with the upper edges of the bag walls straight and even.

To overcome the foregoing difficulty and effect a neater closing seal 9, the present invention contemplates the provision of a novel means for stretching the mouth of the bag preparatory to sealing so that the upper ends of the bag walls are brought together and are straight and even while being sealed. This means utilizes the advance of the carrier to obtain the stretching force and herein comprises a gripper 21 stationarily mounted at the closing station 8 to engage the trailing bag edge I3 while the bag is in motion so as to stretch the bag between the moving and stationary grippers I9 and 21 in the final movement of the bag to the closing station.

In the present instance, the stationary gripper 21 comprises two clamping members 28 (Fig. 3) which are disposed on opposite sides of the bag path for relative movement toward and away from each other and which grip the trailing edge I3 of the bag between opposed clamping surfaces 29. The latter preferably are smooth and nat to engage the bag edge frictionally so that, after the bag is stretched, the edge portion I3 may slip between these surfaces. By permitting the bag edge to slip in this manner, the stretching force is controlled and does not become large enough to rupture the bag. The clamping members 28 are mounted in the same general vertical position as the upper gripper clamp 20, herein just above the latter, to engage the trailing bag edge immediately below the closing seal 9 and act directly opposite the upper clamp. Before the bag is stretched, the clamping members are moved apart to permit the body of the bag to pass between them.

As shown in the drawings, the clamping members 28 may be elongated horizontal arms having the clamping surfaces 29 formed on one end and mounted to swing together to grip the trailing bag edge I3. To support the arms for swinging between the clamping and released positions, shown respectively by full and broken lines in Fig. 3, the rear ends of the arms are fast on the lower ends of vertical rockshafts 3B (Fig. 2) which are journaled in a bracket 13| fastened to the frame I4 in advance of the closing station 3 and projecting over the bag path. Rigidly secured to the rockshafts 30 are levers 32 which project inwardly toward each other and are pivotally connected at their inner ends to the opposite ends of a link 33 thus connecting the arms 29 for swinging in unison but in opposite directions.

Swinging of the gripping arms 28 in timed relation to the advance of the conveyor 5 is achieved through the action of the camshaft I5 and herein the latter energizes a quick acting power actuator 34 which swings the arms just as the trailing bag edge I3 enters between the clamping surfaces 29. The power actuator may be in the form of a piston 35 (Fig. 3) sliding in a cylinder 36 on the bracket 3l and connected to the arms 28 by a lever 31 secured at one end to one of the rockshafts 39 and pivotally joined at the other end to the piston rod 38. The piston is slid outwardly to swing the arms to the clamping position by a suitable operating fluid, such as compressed air, delivered to the cylinder through a supply line 39 and is retracted to return the arms to the released position by a compression spring 49 acting between the piston and the cylinder. A cam 4I on the camshaft moves a follower roller 42 on the actuator 43 of a valve 44 in the supply line 39 to open the Valve when the trailing bag edge I3 is between the clamping surfaces 29. When the valve is opened, the piston slides rapidly to swing the arms 28 into engagement with the trailing edge of the bag. Outward sliding of the piston may be limited by an adjustable stop 45 which determines the amount of inward swinging of the arms 28 and hence the magnitude of the friction between the clamping surfaces 29 and the bag.

In operation, the bag =6 carried by the conveyor 5 is filled while dwelling at the station 1 and then is advanced three steps to the closing station 8. Just before the bag reaches the closing station when the trailing edge I3 is between the clamping surfaces 29, a rise on the cam "4I contacts the follower roller 42 opening the valve 44 to admit compressed air to the cylinder 36 and slide the piston 35 outwardly. The motion of the piston is transmitted through the levers 31 and 32 and the link 33 to the arms 28 which swing in and grip the trailing edge of the bag between the clamping surfaces 29. As a result, the trailing edge is held so that the final movement of the gripper I9 stretches the bag mouth across the width of the bag thus bringing the upper ends of the bag walls together and straightening the latter. If the bag is fully stretched before coming completely to rest, the trailing edge slips between the friction clamping surfaces 29 preventing the bag from rupturing.

While the valve 44 is still open and the arms 28 are in the gripping position holding the bag stretched, the cams 25 swing the levers 24 to move the heated shoes 23 together against the upper edges of the bag walls and form the closing seal 9. The latter, due to the stretching action of the moving and stationary grippers I9 and 21, is comparatively neat and even. Before the next ad- Vance of the conveyor 5, falls on the cams 25 and 4I engage the rollers 26 and 42 moving the shoes back away from the lbag and swinging the arms 28 out to the released position. When the completed bag reaches the end of the conveyor run, the gripper I9 is opened dropping the bag into the chute II.

I claim as my invention:

1. In a packaging machine, the combination of, a carrier, mechanism for advancing said carrier along a predetermined path, a gripper mounted on said carrier for bodily movement therewith and engaging the leading edge of a bag filled and open at one end to advance the bag edgewise along said path to a closing station, two members disposed on opposite sides of said path at said station and mounted for relative movement toward each other and into engagement with the trailing edge of the bag, means normally holding said members apart to permit the body of the bag to pass between the two during advance of said carrier, and anv actuator connected to said members and operable as the bag approaches said station but after said gripper has passed between the members to move the members together and grip the trailing bag edge thereby to stretch the bag in the final movement into said station.

2. In a packaging machine, the combination of a carrier movable along a predetermined path, a gripper mounted on said carrier and engaging the leading edge of a bag open at one end to advance the bag along said path to a closing position, a second gripper stationarily disposed along said path adjacent said position and operable to close and engage the trailing edge of the bag, a quick acting power actuator for closing said second gripper, and a connection between said carrier and said actuator and operable to energize the actuator and close said second gripperas the bag approaches said position thereby to stretch the bag transversely in the nal movement of the bag to said position.

3. Ina packaging machine, the combination of.

mechanism for supporting a bag filled and open at one end and advancing the same edgewise along a predetermined path to a sealing station, said mechanism including a gripper engaging the leading edge of the bag, relatively movable jaws disposed adjacent station and operable to engage the trailing edge of the bag as the bag approaches said station, said jaws having opposed surfaces frictionally engaging said trailing edge to stretch the bag transversely during the final advance of the bag into said station but to permit the bag when stretched to slip between said jaws, and sealing elements disposed at said station and operable after stretching of the bag to engage the bag and close the open end thereof.

4. In a packaging machine, the combination of, a carrier, mechanism for advancing said carrier intermittently, a gripper mounted on said carrier for bodily movement therewith and opening rearwardly to grip the leading edge of a bag which is nlled and open at one end thereby to advance the bag edgewise step by step along a predetermined path, sealing elements disposed at a station along said path and operable to engage opposite sides of the bag across the open end thereof and during dwelling of the bag at said station to seal the same closed, two members mounted on opposite sides of said path at said station, means supporting said members for relative movement toward each other and into engagement with the trailing edge of the bag, and an actuator operable in timed relation to the advance of said carrier to move said members together as the bag approaches said station thereby to stretch the bag in the iinal advance oi" the carrier.

5. In a packaging machine, the combination of, mechanism for supporting a bag nlled and open at one end and advancing the same edgewise step by step along a predetermined path7 said mechanism including a movable gripper engaging the leading edge of the bag, sealing elements disposed at a station along said path and operable during dwelling of the bag at said station to engage the bag at the open end thereof and seal the same closed, a gripper stationarily mounted at said station and operable to close and engage the trailing edge of the bag, and means actuated in timed relation to the advance of said mechanism and connected to said stationary gripper to close the same as the bag approaches said station thereby in the final. advance to stretch the bag between said grippers preparatory to sealing.

6. In a packaging machine, the combination of, a frame, a conveyor mounted on said frame, means for driving said conveyor intermittently along a predetermined path, a gripper mounted on said conveyor to clamp the leading edge of a bag filled and open at one end and advance the bag edgewise step by step along said path and through a closing station, two gripping members mounted on said frame on opposite sides of said path and having opposed clamping surfaces alongside the trailing edge of the bag as the latter approaches said station, means supporting said members for relative movement of said clamping surfaces toward and away from each other, an actuator operated in timed relation. to the advance of said conveyor and connected to said members to move said surfaces into gripping engagement with said trailing edge as the bag approaches said station and hold the trailing edge during the nnal advance of the conveyor and the succeeding dwell thereby to stretch and hold stretched the open bag end, and sealing elements disposed at said station and engageable with the bag the open end thereof during said dwell to seal the bag closed, said actuator being operable to release said clamping surfaces before the next advance of said conveyor.

'7. ln a machine for closing a bag filled and open at one end, the combination of, a carrier movable along a predetermined path, a gripper mounted on said carrier and engaging the leading edge of the bag adjacent the open end thereof to support the bag open end up and advance the same edgewise along a predetermined path to a closing station, a second gripper stationarily mounted along said path and operable to engage the trailing bag edge near the upper end of the bag as the bag approaches said station thereby to stretch the open bag end in the iinal advance of the bag into the station, and sealing elements disposed at said station above said grippers and operable after stretching of the bag to engage the latter across the open end thereof and seal the bag closed.

8. lin a machine for closing a bag lled and open at one end, the combination of7 a carrier movable along a predetermined path, a gripper mounted on said carrier and engaging the leading edge of the bag adjacent the open end thereof to support the bag open end up and advance the edgewise along a predetermined path to a closing station, and a second gripper staticnarily mounted along said path and operable to engage the trailing bag edge near the upper end of the bag as the bag approaches said station thereby to stretch the open bag end in the nal advance of the bag .into the station preparatory to sealing the open end of the bag closed.`

9. In a machine for closing a bag filled and open at one end, the combination of, mechanism for supporting a bag and advancing the same edgewise along a predetermined path to a closing position, said mechanism including a movable gripper engaging the leading edge of 'the bag, and a second gripper stationarily disposed along said path adjacent said position and operable as the bag approaches said position to engage the trailing bag edge thereby to stretch the bag transversely in the nal movement to said position.

References Cited in the file of this patent UNITED STATES PATENTS Number 

